Method and apparatus for making and breaking electrical circuits



June 22 1926. l LSQQ F. LOWENSTEIN METHOD AND APPARATUS FOR MAKING AND BREAKING ELECTRICAL CIRCUITS Filed May 1, 1918 Nr.5 w

' Frz ZLZ Zowene on Patented June 22, 1926.

N UNITED .STATES FRITZ LOWENSTEI'N, YORK, N. Y.

FRITZ rI OUVERS'JIEIN, DECEASED, ASSIGNOR, -BY MESNE ASSIGNMENTS, T0 PATENTS CORPORATION, A DlVliS'lIC CORPORATION.

PATENT :or-FICE; g

;`1'OI-IN".C. `WAIT, ADMINISTRATOR OF SAID METHOD AND APPABATUS-EOR1MAKfING AND BREAKING ELECTRICAL CIRCUITS.

Application filed `May v1,

This invention relates to rmethods of kand apparatus for making and `lmeaking elec* trical circuits; and more particularly .it re- ;lates-to closing .and opening heavy current 5 circuits through -the approach and separation of :relatively movable contacts or terminals in such a circuit, such relative move- :ment `being Very small' as compared with :that heretofore employed :and considered necessary1 in practice. Thatis'to say, whereas it has lbeen customary heretofore :to elnploy gap openings of an order yof :magnitude of a thirty-second of an inch or more, the present invention [involves the 'employ- `ment of gap ,openings lof Yonly .a few "thousandths of an inch. Obviously ,the normal circuit voltage `must :not be 'high enough to breakdown a gap ,of thesmall magnitude rhere lin question. In other words, fthe invention .is ,applicable :more :particularly "to icircuits oficomparatively low voltage.

,In `:opening circuits carrying relatively heavy l currents, :much difficulty .has rb een `l`en- `:countered heretofore byu'reason of the arcing which occurs when rsuch circuits are broken inthe usual manner. Not lonly pare :the ter- -minals .of :the 'commonly :employed switches vor .other circuiteinterrnpting :devices iso rapidly!:pitted 4and -eventually :rendered un serviceable as fto. make frequent replacement necessary, but kalso there `is .often {considerable dangerand inconvenience in @operating .such devices. The many attempts Aheretofore I.ricade :to tprevent such :arcing 'or .to minimize its eiects,have been'only .partially successful at best and have :resulted in no :thoroughly satisfactory `solution lof `.the problem. y

.I `.have :discovered that the iarcing ordinarily .caused by ropening 1a heavy current circuit fcan'be practieallyeliminated orsuppressed -to any :desired extent -zby restricting the width voi" the circuitabreaking egap to :a relativelyminute idistancevwhose' order .of magnitude corresponds to a few lfthcmsandths `of an inch. By this .simple .expedient the formation of an are between the V:relatively ymovable `terminals or contacts lwhere :the -heavy current circuit'is opened may `be entirely or Ylargely suppressed; while on the other hand separating said contacts .the greater distance required by the ,prior ipractice, all :other conditionsxiremaining iidentically :the same, Vproduces violent arcing.

191,8. Serial .No. 231,840.

Nofattempt `is .made here ,to explain this ,phenomenon on theoretical grounds, -but .the established factisnoted as a most 1important .advantage attained .in the practice of ymy linvention. l i

i While :the principles of the invention .are to be .understood as of .general application7 ithey are of especial utility fin the art 'fof radio signaling where the high tension l,and high vfrequency :impulses :or wave trains lradiated from the sending station are ythe gultimate result, through 4intermediate means, ,of 3 repeatedly making and breaking a .power ksupply circuit \.of comparatively ,high amperage. Accordingly 4the application `of the invention to radio transmission, ,and respe- ;clallyfto @radio telegraphy, will be herein `afterdescribed by Way of ya ,typical concrete :embodiment .of the broad principles ofthe invention, ywithout implying :thereby 'any v,limitation of the invention to such use.

A radio transmitter system lof the type commonly used-atthe present time comprises va power vcircuit `feeding the primary cfa power transformer, whose secondary Vin turn feeds. thesoecalled 4,closed or oscillation ,circuit,xvhich latter energizes the antenna or radiating circuit. `The power circuit is 4normally open, 4when the transmitter is not .in iuse, but -by intermittently `closingg said power circuit for periods'of varying :length corresponding to .the "dots and ydash'esgof Va v @telegraphc code, the `.desi-red oscillationsare set iup `.in the I,closed :oscillation circuit ,and fby .it transferred to the Lopen orv antenna circuit v'for radiation ,An instrument .simil- `lar in general to the `ordinary .telegraph y,sending key is usually `,employed .to make and break .the power circuit inithe 4.manner described. As the current in :the power circuit iis relatively heavy, farci'ng` at the they 1hasalwaysbeen a source :of constant vtrouble, and iitiis'in this connection that my 4ment of @the make-and-break contactsto .-a

very small distance, vsay 'afromyiive Ito Iten `(mesthousandths of an inch, `for example, arcing is substantially eliminated. Ina ytypical instance, the voltage :of the lpower .circuit may be 200 volts yor zthereabout, .for

example.

The new method can .be Ypracticed with circuit-breaking devices of various forms, but the novel form of transmitter key illustrated in the accompanying drawings is especially suitable for radio signaling work and has given excellent results in actual service. In the drawings- Fig. 1 represents a complete transmitter' key in plan;

Fig. 2 is a side elevation of same; and

Figs. 3 and 4 are detail vertical and horizontal sections on a larger scale.

Referring to the drawings, the several parts of the. key device are mounted on a substantial base 10 of suitable insulating material. Secured to this base are conducting castings 11 and 12. The conductor 11 is a substantially fiat strip except at one end where it extends upwardly a short distance, forming a pedestal to support the. lower and stationary contact disk 13 which is most desirably made of silver. The other conductor 12, extends upwardly from the base for some distance and then horizontally to form an overhanging supporting bracket.v The conductors may be anchored to the insulation base in any suitable manner. In the present instance screws 1e are provi-ded. for this purpose, being received in countersinks formed in the under side of the base and extending upwardly to cooperate with nuts 15 to form binding posts for suitably connecting the key in a power circuit. The opposite end` of conductor 11 is similarly anchored to the insulating base by a screw 16. After the anchorage screws are in position, the countersinks may be pluggedwith sealing wax or the like as indicated at 17.

The upper and movable silver contact disk 18 is carried on the operating arm 19, whose bifurcated end 20 embraces the relatively broad upright portion of supporting conductor 12, and is pivotally connected thereto by means of the assembling and pivot pin 21, which is held rigid with member 12 by set screws 22. By thus pivoting member 19 on two fixed bearing points widely spaced apart, any lateral play of said member 19,

'due to wear in the bearings, is reduced to a minimum. A coiled spring 23 confined between' the operating arm and a cupped adjusting nut 24, working on screw 25 mounted in the base, normally presses the operating arm upwardly and tends to separate contacts 13 and 18. The upward movement of the operating arm is limited by stop means of suitable character. In the present example this stop means is of a special design which has been found to be particularly useful with a sending key of this character where the gap or opening between the key contacts in breaking the circuit should be limited to a very small maximum but at the same time should be adjustable below that maximum to a certain extent. To this end, the overhanging arm of member 12, as here shown, is provided with two stops 26 and 27, of which one, 26, is a screw adapted to be set in xed position corresponding` to the maximum Contact opening and is not intended to be adjusted during the operation of the key; while the other stop 27, is formed by a screw which can be set to give any desired gap opening between zero and the maximum permitted by the stop screw 26. The adjustable stop screw 27 may be locked in any desired position by means of thumb nut 28. In the specific example here shown the stop screw 26 performs a ldouble function in that it also cooperates with nut 29 to press one terminal of iiexible braided conductor 30 firmly into contact with conductor 12, the other terminal of said conductor being similarly held in Contact with the operating arm 19, by means of binding screw 31, and nut 32. It is to be noted that the combined stop and binding screw 26 extends loosely through the conductor 12 and occupies its correct position as a permanent stop only when nut 29 is draw firmly up into good contact with the terminal of the flexible lead 80. This construction has certain desirable practical advantages.

In a typical example, the faces of the circular silver contact disks 13 and 18 may be one-half inch to fiVe-eighths inch in diameter, and the fixed stop 26 may permit a maximum gap opening of say 0.015 to 0.020 inch, a distance which may be characterized, for convenience in reference, as corresponding in order of magnitude to a hundreth of an inch. The best operating distance is between 0.005 and 0.010 inch as before stated. Such a key can be used practically indefinitely with circuits carrying as high as 60 amperes, without arcing to an excessive extent; whereas, with transmitter keys of comparable size heretofore in use, operation at higher than about 35 to 40 amperes was accompanied by excessive arcing, and the rapid destruction of the Contact members compelled frequent replacement.

What I claim is:

`1. transmitter key comprising the combination, with cooperating relatively movable inake-and-break contacts and appropriate operating means therefor, of resilient means tending to separate said contacts, fixed stop means restricting such separation to a maximum distance not substantially exceeding one one-hundredth of an inch, and adjustable stop means for varying the permissible separation between zero and the upper limit.

2. A transmitter key comprising the coinbination, with cooperating relatively movable make-and-break cont-acts and appropriate operating means therefor, of resilient means tending to separate said contacts, combined terminal-clamping and stop means restricting such separation to a predetermined distance, and adjustable stop means for fine adjustment of the separating distance permitted by the iixed stop.

3. A transmitter key comprising the combination, with cooperatingl relatively movable make-and-break contacts and appropriate operating means therefor, of resilient means tending to separate said contacts, a movable stop member arranged, when in operative position, to limit -the separation of said contacts to a predetermined maximum distance, and at the same 1 time to lirmly clamp a conducting lead in place.

4. A transmitter key comprising; the combination, with cooperatingrelatively movable make-and-break contacts and appropriate operatingmeans therefor, of resilient means tending` to separate said contacts, a stop screw arranged, when turned down into limiting` position, to restrict the separation of said contacts to a distance not substantially exceeding 0.015 to 0.020 inch and a terminal .member arranged to be iirmly clamped 1n place by said screw only When the latter is in its limiting` position aforesaid.

5. A malte-and-break key of the character described, comprising a pair of cooperating contacts, a movable operating arm carrying one of said contacts and having a bifurcated portion, a relatively broad supporting member embraced by said bifnrcated portion, an assembling and pivot pin extending through said supporting member and said bifurcated portion of the operatingarm to provide spaced pivot bearings therefor, and means for holding said pin rigid With said supporting member.

In testimony whereof I hereunto aiiiX my signature.

u FRITZ LOVVEN STEIN. 

